The invention relates to an X-ray fluorescence spectrometer for the analysis of a solid or liquid sample disposed in a measuring position inside a compact sample chamber of a volume of .ltoreq.10 dm.sup.3 preferably &lt;1dm.sup.3, on a sample holder. The sample has a maximum linear extension of 1 dm. An X-ray tube is projecting into the sample chamber for irradiating the sample, and a detector is arranged in a detector chamber, wherein the detector chamber can be separated in a vacuum tight manner from the sample chamber by means of a shutter element.
An X-ray fluorescence spectrometer of this type is e.g. known from the device "SRS 3400" described in the company leaflet "SPECTROMETRY SOLUTIONS SRS 3400 mit SPECTRA.sup.plus " of the company Bruker AXS GmbH dated 1997.
In order to examine the composition of a test sample--in an X-ray fluorescence spectrometer--X-rays are usually irradiated onto a surface of the sample, and the X-ray fluorescence radiation emitted by the sample is detected, the wavelength distribution of which being characteristic for the elements present in the sample, while their intensity distribution--gives information about the relative abundance of the sample components. By means of a spectrum obtained in this manner, the expert is able to determine to a relatively exact extent the components and quantitative proportions of the examined test sample.
During a measurement, the sample is usually held in a fixed measuring position in the sample chamber. If necessary, it can also be rotated. The sample chamber is either evacuated during the measurement or is flooded with an inert gas, usually helium. In order to establish acceptable measuring conditions, the sample chamber must be connected to a suitable pumping system since, during introduction of a new test sample into the sample chamber, air from the surrounding atmosphere enters the sample chamber which must be removed again from this location prior to the actual measurement.
For charging the sample chamber with a test sample and subsequent elimination of incoming atmospheric air, known X-ray fluorescence spectrometers comprise a transfer chamber which can be evacuated and through which the test sample to be examined can be introduced from the outside. In this way, the sample chamber itself is at first disconnected from the outer atmosphere. The transfer chamber is not opened towards the sample chamber until the transfer chamber has been closed and evacuated (or after thorough flushing with inert gas) and the sample can be transferred to its measuring position.
A disadvantage of the known X-ray fluorescence spectrometers is their construction which requires a lot of space owing to the transfer chamber, and also the relatively high production costs for the complicated construction of the transfer chamber and sample chamber system. The mode of operation for this system in which at first the sample chamber has to be vacuum-disconnected from the transfer chamber, and then the transfer chamber has to be subjected to atmospheric pressure, charged with the sample, and subsequently sealed off again from atmosphere and evacuated, whereupon the sample chamber is opened towards the transfer chamber and the sample is transported to its measuring position and subsequently the sample chamber is again sealed off from the transfer chamber and finally subjected to a measuring vacuum or flooded with the corresponding inert gas, is not only very time consuming but also relatively vulnerable to errors occurring during the complicated individual steps.
A further disadvantage consists in that the sample chamber cannot be accessed directly from the outside and therefor the entire system has to be dismounted for any modifications, repairs or maintenance works within the sample chamber which requires a high amount of time and effort.
The fact that the system comprises a transfer chamber and a sample chamber requires also complicated internal transport means for transporting the sample out of the transfer chamber into the measuring position inside the sample chamber which step is also vulnerable to operational errors.
In contrast thereto, it is the object of the present invention to improve an X-ray fluorescence spectrometer of the initially described type in such a manner that its mechanical construction is rendered more compact and considerably simpler such that charging of the sample chamber with a test sample becomes less difficult, that the operational steps of the required gas exchange between the chambers involved are facilitated, that operational safety is increased and that maintenance and repair works on the sample chamber itself are facilitated.